I have been hosting some of my websites with Site5 for about a year now. I also have other websites hosted in other web hosting companies. Here is my review for site5 based on my own personal experience with them
Why I choose Site5
I got to know about Site5 through the webhostingtalk forums. At that time, I was searching for a reliable and reputable cheap web hosting company for a couple of my new websites. And I’ve heard a lot of good reviews about Site5 and so decide to try them out. Since they have a 60 day money back refund, I figure if I did not like it, I would ask for my money back.

Anyway, I was basically testing their web hosting on my new websites so I was not terribly affected.
Site5 Hosting Plan
Site5 only offer two types of hosting plan : shared and reseller. So I took the superhosting extreme package. Basically here’s the brief web hosting package details :
Diskspace : 8GB
Bandwidth : 500GB
Multisite Accounts : 5
Unlimited : domain pointers, ftp, mysql
It also comes with fantastico, cpanel. All this for about $109 annually which is pretty cheap.

Please note this hosting plan is no longer available and is replaced with multisite dynamite plan. It is basically the same as my previous plan except for more diskspace and bandwidth. As I’m writing this, they have a promotion where you can get this hosting plan for 2 years at only $149 which I consider to be a good deal.
Unique Features of Site5 hosting
One feature I like about site5 hosting is the multisite accounts. It is basically a full featured control panel for each domain. Unlike other shared web hosting companies which uses domain pointers, a multisite accounts exists on its own with its own subdomains, domain pointer, ftp, mysql etc. This help me to organize my websites better especially if you have a lot of domains. You can set the diskspace and bandwidth from the main pool of your web hosting account.
The other feature is the flashback which allows you to undo any changes you make to your website. It is a life saver especially when a website breaks down and you do not know the cause.

Things that can be improved
Though I like Site5 and would recommend it to friends, there are a few things that could make it better. One of them is the upgrade option. I recently upgraded my hosting plan to multisite dynamite and was told I had to shift to another server. The problem was I had to do the data transfer myself. With 3GB of data to transfer, not to mention the dozens of ftp, mysql and email accounts, it was a real hassle. Something I am sure their staff could have easily completed in a short time.
The other thing I didn’t like was I could not request for more IP addresses. If you know about SEO, then you know how having multiple IP addresses can be useful.
In all, I would still recommend site5 due to its cheap web hosting plan, good support and high availability.